1. Technical Field
The present disclosure relates to laser apparatuses.
2. Related Art
In recent years, semiconductor production processes have become capable of producing semiconductor devices with increasingly fine feature sizes, as photolithography has been making rapid progress toward finer fabrication. In the next generation of semiconductor production processes, microfabrication with feature sizes at 60 nm to 45 nm, and further, microfabrication with feature sizes of 32 nm or less will be required. In order to meet the demand for microfabrication at 32 nm or less, for example, an exposure apparatus is being developed which combines an apparatus for generating extreme ultraviolet (EUV) light at a wavelength of approximately 13 nm with a reduced projection reflective optical system.
Three kinds of apparatuses for generating EUV light are generally known including a Laser Produced Plasma (LPP) type apparatus in which plasma is generated by irradiating a target material with a laser beam, a Discharge Produced Plasma (DPP) type apparatus in which plasma is generated by electric discharge, and a Synchrotron Radiation (SR) type apparatus in which orbital radiation is used to generate plasma.